Supercritical carbon dioxide turbine thrust self-balancing system and monitoring method

Abstract

The present application relates to the field of turbine technology, and particularly relates to a supercritical carbon dioxide turbine thrust self-balancing system and a monitoring method, comprising a turbine end, a balancing end, a high-speed generator, a main shaft, a casing and a monitoring assembly, the main shaft provides installation conditions for the high-speed generator, the balancing end is used for balancing the turbine thrust, the high-speed generator is used for outputting power, and the monitoring assembly is used for monitoring the turbine shaft system thrust, the system monitors the turbine shaft system pressure through the monitoring assembly, and calculates and judges whether the shaft system thrust difference is greater than the thrust bearing capacity, if greater, a shutdown signal is sent, and if less than or equal to, operation is carried out, so that the thrust does not exceed the capacity in all working conditions, and the problem that the axial thrust generated by the existing single-suspension turbine is much greater than the maximum capacity of the thrust bearing is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of turbine technology, in particular to a supercritical carbon dioxide turbine thrust self-balancing system and monitoring method. BACKGROUND

[0002] The closed cycle power system with supercritical carbon dioxide as working medium can greatly reduce the size of turbine and compressor and other equipment, has the advantages of high energy density, small compression power consumption, no phase change in cycle, less initial investment and low operation cost, and is considered as the best solution for future power systems.

[0003] The supercritical carbon dioxide turbine is an important component in the thermal cycle system for converting heat energy into mechanical energy, generally adopts a single cantilever turbine, and then uses a direct drive high-speed generator, or drives a general generator through a coupling after speed reduction through a gear box, which can reduce the thermal load of the unit and the aerodynamic loss caused by the inter-stage pipeline compared with the double cantilever turbine. At present, the supercritical carbon dioxide turbine mainly uses oil film bearing, and the linear speed has a limit value, so the capacity of the thrust bearing has a maximum value, and the axial thrust generated by the single cantilever turbine is much larger than the maximum capacity of the thrust bearing. SUMMARY

[0004] The present application aims to provide a supercritical carbon dioxide turbine thrust self-balancing system and monitoring method, which aims to solve the problem that the axial thrust generated by the existing single cantilever turbine is much larger than the maximum capacity of the thrust bearing.

[0005] To achieve the above-mentioned purpose, in a first aspect, the present application provides a supercritical carbon dioxide turbine thrust self-balancing system, comprising a turbine end, a balancing end, a high-speed generator, a main shaft, a casing and a monitoring assembly, wherein the high-speed generator is arranged in the casing, the main shaft is rotationally connected with the high-speed generator and penetrates through the high-speed generator, the turbine end is arranged on one side of the main shaft, the balancing end is arranged on the other side of the main shaft, and the monitoring assembly is arranged outside the casing.

[0006] The monitoring assembly comprises a transmitter group, an input signal line, a PLC control module and an output signal line, the transmitter group is arranged outside the casing, the input signal line is electrically connected with the transmitter group and the PLC control module, and is located between the PLC control module and the transmitter group, and the output signal line is electrically connected with the PLC control module.

[0007] The turbine end comprises a nozzle ring set, a turbine disc set, a pull rod screw, a labyrinth seal and a turbine end dry gas seal dynamic and static ring set, the turbine disc set is arranged on the side of the main shaft, the pull rod screw is fixedly connected with the main shaft and penetrates the turbine disc set, the nozzle ring set is arranged outside the turbine disc set, the labyrinth seal is arranged on the side of the main shaft close to the nozzle ring set, and the turbine end dry gas seal dynamic and static ring set is arranged on the side of the labyrinth seal away from the nozzle ring set.

[0008] The balance end comprises a balance end dry gas seal dynamic ring and a balance end dry gas seal static ring, the balance end dry gas seal dynamic ring is arranged on the side of the main shaft away from the turbine end dry gas seal dynamic ring set, and the balance end dry gas seal static ring is arranged in the casing and abuts against the balance end dry gas seal dynamic ring and is located on the side away from the main shaft.

[0009] In a first aspect, the application further provides a supercritical carbon dioxide turbine thrust self-balancing monitoring method, comprising the following steps:

[0010] The initial monitoring data is obtained by monitoring the turbine shaft system pressure value through the monitoring component;

[0011] The monitoring component calculates and obtains the thrust difference based on the built-in program on the initial monitoring data;

[0012] It is judged whether the thrust difference is greater than the thrust bearing capacity, and if so, a shutdown signal is sent, otherwise, the operation is carried out.

[0013] The main shaft is connected with the high-speed generator (gearbox) through a bearing, penetrates the high-speed generator, extends into the turbine end and the balance end, the main shaft can rotate freely in the high-speed generator (gearbox), the balance end is used for balancing the turbine thrust, the high-speed generator is used for outputting power, and the monitoring component is used for monitoring the turbine shaft system thrust, the system monitors the turbine shaft system pressure through the monitoring component, and judges whether the thrust difference of the thrust shaft system is greater than the thrust bearing capacity, and if so, a shutdown signal is sent, otherwise, the operation is carried out, so that the thrust does not exceed the capacity in all working conditions, and the problem that the axial thrust generated by the existing single suspension type turbine is much greater than the maximum capacity of the thrust bearing is solved. BRIEF DESCRIPTION OF DRAWINGS

[0014] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiment or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creating laborious work.

[0015] Fig. 1 is a structural schematic diagram of a supercritical carbon dioxide turbine thrust self-balancing system provided by the present application.

[0016] Fig. 2 is a monitoring component connection schematic diagram of a supercritical carbon dioxide turbine thrust self-balancing system provided by the present application.

[0017] Fig. 3 is a flow chart of a supercritical carbon dioxide turbine thrust self-balancing monitoring method provided by the present application.

[0018] 1-inlet pipe, 2-fourth pressure transmitter, 3-first stage nozzle ring, 4-second stage nozzle ring, 5-third stage nozzle ring, 6-casing, 7-fourth stage nozzle ring, 8-third pressure transmitter, 9-exhaust pipe, 10-labyrinth seal, 11-second pressure transmitter, 12-balancing pipe, 13-flow meter, 14-signal line, 15-regulating valve, 16-pipe, 17-dry gas seal gas source, 18-first pressure transmitter, 19-main shaft, 20-balancing end dry gas seal dynamic ring, 21-balancing end dry gas seal static ring, 22-vortex end dry gas seal static ring, 23-vortex end dry gas seal dynamic ring, 24-fourth stage turbine disc, 25-third stage turbine disc, 26-second stage turbine disc, 27-first stage turbine disc, 28-pull rod screw, 29-exhaust cavity, 30-vortex end dry gas seal cavity, 31-balancing cavity, 32-input signal line, 33-PLC control module, 34-output signal line. DETAILED DESCRIPTION

[0019] Embodiments of the present application are described in detail below with reference to examples illustrated in the accompanying drawings, in which the same or similar components or components having the same or similar functions are denoted by the same or similar reference numerals throughout. The embodiments described below by reference to the accompanying drawings are exemplary and are intended to explain the present application, and cannot be understood as limiting the present application.

[0020] In a first aspect, referring to Figs. 1 to 3 , the present application provides a supercritical carbon dioxide turbine thrust self-balancing system, comprising a turbine end, a balancing end, a high-speed generator, a main shaft 19, a casing 6, and a monitoring component, the high-speed generator is arranged in the casing 6, the main shaft 19 is rotationally connected with the high-speed generator and penetrates through the high-speed generator, the turbine end is arranged on one side of the main shaft 19, the balancing end is arranged on the other side of the main shaft 19, and the monitoring component is arranged outside the casing 6.

[0021] Specifically, the main shaft 19 is connected with the high-speed generator (gearbox) through a bearing, penetrates through the high-speed generator, extends into the turbine end and the balance end, the main shaft 19 is freely rotatable in the high-speed generator (gearbox), the balance end is used for balancing the turbine thrust, the high-speed generator is used for outputting power, the monitoring assembly is used for monitoring the turbine shaft thrust, the system monitors the turbine shaft pressure through the monitoring assembly, and judges whether the shaft thrust difference is greater than the thrust bearing capacity, greater than the stop signal, less than or equal to the operation, can realize that the thrust is not over capacity in all working conditions, and solve the problem that the axial thrust generated by the existing single suspension type turbine is much greater than the maximum capacity of the thrust bearing.

[0022] Further, the monitoring assembly comprises a transmitter group, an input signal line 32, a PLC control module 33 and an output signal line 34, the transmitter group is arranged outside the casing 6, the input signal line 32 is electrically connected with the transmitter group and is electrically connected with the PLC control module 33 and is located between the PLC control module 33 and the transmitter group, and the output signal line 34 is electrically connected with the PLC control module 33.

[0023] Specifically, the pressure of the turbine end dry gas seal cavity 30 is measured by the second pressure transmitter 11, the pressure value is P2, the supercritical carbon dioxide enters the turbine through the inlet pipe 1, the inlet pressure is measured by the fourth pressure transmitter 2, the pressure value is P4, after working through the nozzle ring group and the turbine disc group, enters the exhaust cavity 29, and is discharged through the exhaust pipe 9, the exhaust pressure is measured by the third pressure transmitter 8, the pressure value is P3, and the pressure difference between the exhaust cavity 29 and the exhaust pressure P3 is very small, so they can be considered as equal.

[0024] Further, the turbine end comprises a nozzle ring group, a turbine disc group, a pull rod screw 28, a labyrinth seal 10 and a turbine end dry gas seal movable and static ring group, the turbine disc group is arranged on one side of the main shaft 19, the pull rod screw 28 is fixedly connected with the main shaft 19 and penetrates through the turbine disc group, the nozzle ring group is arranged outside the turbine disc group, the labyrinth seal 10 is arranged on the side of the main shaft 19 close to the nozzle ring group, and the turbine end dry gas seal movable and static ring group is arranged on the side of the labyrinth seal 10 away from the nozzle ring group.

[0025] Specifically, the nozzle ring group and the turbine disc group are arranged alternately, the nozzle ring group comprises a first-stage nozzle ring 3, a second-stage nozzle ring 4, a third-stage nozzle ring 5 and a fourth-stage nozzle ring 7, and is arranged in the casing 6 in sequence, the turbine disc group comprising a first-stage turbine disc 27, a second-stage turbine disc 26, a third-stage turbine disc 25 and a fourth-stage turbine disc 24 is arranged on the main shaft 19 in sequence through the pull rod screw 28, the labyrinth seal 10 is arranged in the casing 6 behind the exhaust cavity 29, the turbine end dry gas seal dynamic ring 23 is arranged behind the labyrinth seal 10, and the turbine end dry gas seal static ring 22 is arranged in the casing 6 and abuts against the turbine end dry gas seal dynamic ring 23 with a small gap, so that the turbine end dry gas seal cavity 30 is formed between the turbine end dry gas seal dynamic ring 23 and the labyrinth seal 10.

[0026] Further, the balance end comprises a balance end dry gas seal dynamic ring 20 and a balance end dry gas seal static ring 21, the balance end dry gas seal dynamic ring 20 is arranged on the side of the main shaft 19 away from the turbine end dry gas seal dynamic ring group, and the balance end dry gas seal static ring 21 is arranged in the casing 6 and abuts against the balance end dry gas seal dynamic ring 20 and is located on the side away from the main shaft 19.

[0027] Specifically, the balance end dry gas seal dynamic ring 20 is arranged at the end of the main shaft 19, and the balance end dry gas seal static ring 21 is arranged in the casing 6 to form a balance cavity 31, the pressure of which is measured by the first pressure transmitter 18, and the pressure value is P1.

[0028] The dry gas seal gas source 17 is connected to the balance cavity 31 through the pipeline 16, the balance cavity 31 is connected to the turbine end dry gas seal cavity 30 through the balance pipeline 12, the balance pipeline 12 is provided with an adjusting valve 15, the opening of which is feedback controlled by the flowmeter 13 through the signal line 14, so that the flowmeter 13 is always set to a certain value.

[0029] The sealing gas flows from the dry gas seal gas source 17 to the balance cavity 31 through the pipeline 16 to generate a thrust, and then flows through the balance pipeline 12 and the adjusting valve 15 to be injected into the turbine end dry gas seal cavity 30, and then flows through the labyrinth seal 10 as cooling gas to cool the casing 6 and the main shaft 19, and finally is injected into the exhaust cavity 29 to be mixed into the main flow and discharged, so that one stock of sealing gas is used for two dry gas seal points, the amount of sealing gas is reduced, and the power generation efficiency of the system is improved.

[0030] The balance cavity 31 has a pressure area A1, and the pressure value P1 is measured by the first pressure transmitter 18, the balance end thrust is F1=A1*P1, and the direction is directed to the turbine end; the dry gas seal cavity 30 of the turbine end has a pressure area A2, and the pressure value P2 is measured by the second pressure transmitter 11, the thrust is F2=A2*P2, and the direction is directed to the balance end; the thrust generated by the aerodynamic force and the inter-stage pressure difference on the turbine disc group is F3, and the direction is directed to the balance end, F3 is related to the inlet pressure P4 and the exhaust pressure P3, P4 is measured by the fourth pressure transmitter 2, and P3 is measured by the third pressure transmitter 8, and each determined inlet and exhaust pressure P4, P3 can be determined by the through-flow part aerodynamic simulation calculation.

[0031] The dry gas seal gas source 17 is high-pressure storage tank from the compressor outlet in the power generation system, and the gas after being heated and filtered, the pressure P1 of the balance cavity 31 is equal to the compressor outlet pressure minus the sealing pipeline loss, the turbine inlet pressure P4 in the supercritical carbon dioxide power generation system is equal to the compressor outlet pressure minus the main flow pipeline loss, according to experience, P1 and P4 change consistently and the difference is not large, for a unit below 1000kW, -1MPa≤P1-P4≤1MPa; since the required cooling flow at the turbine end is certain, that is, the value of the flow meter 13 is unchanged, the pressure P2 of the dry gas seal cavity 30 of the turbine end is greater than the exhaust pressure P3, and changes with P3 and is not greater than P1, that is, P3≤P2≤P1.

[0032] Considering the values of the turbine inlet and outlet pressures P4, P3 that may appear in the running process under different working conditions, F3 is simulated and determined; the balance cavity pressure P1=P4+k (according to experience, -1MPa≤k≤1MPa), there are upper and lower limits, A1 is determined, then F1 has upper and lower limits; the dry gas seal cavity pressure P2 of the turbine end is greater than P3 and P2≤P1, there are upper and lower limits, A2 is determined, then F2 has upper and lower limits; for each group of determined P4 and P3, the upper and lower limits of P1 and P2 can be obtained, and thus the upper and lower limits of F1 and F2 are obtained; therefore, for each working condition, the upper and lower limits of the resultant force of F1, F2 and F3, that is, the shaft system thrust, can be obtained, and through calculation, the upper and lower limits of the shaft system thrust value under various working conditions are within the bearing capacity range.

[0033] The second aspect, please refer to Fig. 3 The application provides a supercritical carbon dioxide turbine thrust self-balancing monitoring method, which comprises the following steps:

[0034] S1, monitoring the shaft system pressure value through a monitoring assembly to obtain initial monitoring data;

[0035] Specifically, the shaft system pressure value is monitored through a PLC monitoring assembly, and an input signal line 32 is transmitted into a PLC control module.

[0036] The S2 monitoring component calculates the difference of the initial monitoring data based on the built-in program to obtain a thrust difference;

[0037] Specifically, the measured balance cavity pressure P1 and the vortex end dry gas seal cavity pressure P2 are input into the PLC control module through the input signal line 32, and the balance end thrust F1 and the vortex end dry gas seal thrust F2 can be calculated through the built-in program of the PLC control module. The measured turbine inlet pressure P4 and the exhaust pressure P3 are input into the PLC control module, and the vortex end thrust F3 can be obtained through the built-in program. The absolute value |F1-F2-F3| of the thrust difference is calculated, that is, the thrust difference.

[0038] S3 judges whether the thrust difference is greater than the thrust bearing capacity. If it is greater, a shutdown signal is sent out, and if it is less than or equal to, the operation is performed.

[0039] Specifically, the PLC control module judges whether |F1-F2-F3|≤thrust bearing capacity FT is true. If it is true, the operation continues, otherwise a shutdown signal is sent out through the output signal line 34.

[0040] The above only discloses a preferred embodiment of a supercritical carbon dioxide turbine thrust self-balancing system and monitoring method of the present application, of course, cannot limit the scope of the present application, those skilled in the art can understand that all or part of the above-mentioned embodiments can be implemented, and equivalent changes made according to the claims of the present application still belong to the scope covered by the present application.

Claims

1. A supercritical carbon dioxide turbine thrust self-balancing system, characterized in that, it comprises a turbine end, a balance end, a high-speed generator, a main shaft, a casing and a monitoring assembly, the high-speed generator is arranged in the casing, the main shaft is rotationally connected with the high-speed generator and penetrates through the high-speed generator, the turbine end is arranged on one side of the main shaft, the balance end is arranged on the other side of the main shaft, and the monitoring assembly is arranged outside the casing; the turbine end comprises a nozzle ring group, a turbine disc group, a pull rod screw, a labyrinth seal and a turbine end dry gas seal dynamic and static ring group, the turbine disc group is arranged on one side of the main shaft, the pull rod screw is fixedly connected with the main shaft and penetrates through the turbine disc group, the nozzle ring group is arranged outside the turbine disc group, the labyrinth seal is arranged on the side of the main shaft close to the nozzle ring group, and the turbine end dry gas seal dynamic and static ring group is arranged on the side of the labyrinth seal away from the nozzle ring group; the balance end comprises a balance end dry gas seal dynamic ring and a balance end dry gas seal static ring, the balance end dry gas seal dynamic ring is arranged on the side of the main shaft away from the turbine end dry gas seal dynamic and static ring group, and the balance end dry gas seal static ring is arranged in the casing and abuts against the balance end dry gas seal dynamic ring and is located on the side away from the main shaft.

2. The supercritical carbon dioxide turbine thrust self-balancing system according to claim 1, characterized in that, the monitoring assembly comprises a transmitter group, an input signal line, a PLC control module and an output signal line, the transmitter group is arranged outside the casing, the input signal line is electrically connected with the transmitter group and the PLC control module and is located between the PLC control module and the transmitter group, and the output signal line is electrically connected with the PLC control module.

3. A method for monitoring thrust self-balancing of a supercritical carbon dioxide turbine, applied to a thrust self-balancing system of a supercritical carbon dioxide turbine according to claim 1, characterized in that, comprising the following steps: monitoring the turbine shafting pressure value by the monitoring assembly to obtain initial monitoring data; calculating the initial monitoring data by the monitoring assembly based on the built-in program to obtain a thrust difference; judging whether the thrust difference is greater than the thrust bearing capacity, greater than which a shutdown signal is sent, and less than or equal to which the operation is performed.

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